1. Field of the Invention
The present invention relates to a rotor shaft mechanism, and particularly to a rotor shaft support mechanism in a smallsized oscillator such as a UHF oscillator incorporated in an RF modulator. Specifically, the present invention relates to a rotor shaft support mechanism for supporting a rotor shaft of a variable capacitor mounted on a frame.
2. Description of the Prior Art
FIG. 1 is an exploded perspective view showing the schematic structure of an example of the conventional RF modulator. In such a device, a circuit board 2 is provided in a shielding casing 1 and a connection plug 3 for externally connecting a circuit formed on the circuit board 2 is provided on a side plate of the shielding casing 1. A slot 2a is formed at a part of the circuit board 2, so that a UHF oscillator 4 is fixed in the slot 2a. This oscillator 4 is constituted by a metal frame 5 and a cover 6 covering the frame 5 in which a variable capacitor 8 is contained together with various kinds of electronic parts 7 such as transistors, diodes, resistors, etc. A rotor shaft 8b of the variable capacitor 8 is supported in holes formed in the side plates of the frame 5. A plurality of rotor vanes 8a are fixed on the rotor shaft 8 and stator vanes ( not shown ) are fixedly provided inside the frame 5 in opposition to the rotor vanes 8a. The rotor shaft 8b is inside of an operation hole 1a bored in the shielding casing 1 so that it can be adjusted from the outside of the shielding casing 1 by rotating the rotor shaft 8b.
Such an RF modulator shown in FIG. 1 is to be incorporated into a VTR product. Recently, as the varieties of the VTR products increase, the kinds of the RF modulator also increase in dimension and in operation mode. Thus, among the UHF oscillator products, there is no standard in the way to provide the variable capacitor 8 in the frame 5, that is in connection with the direction of the rotor shaft 8b.
In view of the above-mentioned circumstances, conventionally, the design of RF modulators or the like has been carried out in accordance with the kinds of VTR products, and the arrangement of the RF modulator and the UHF oscillator 4 to be incorporated into the RF modulator is different for each product. Thus, it is very difficult to establish standardization in design of the UHF oscillator 4.